/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package com.apptentive.android.sdk.view;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.os.Bundle;
import android.os.Parcel;
import android.os.Parcelable;
import androidx.core.view.AccessibilityDelegateCompat;
import androidx.core.view.InputDeviceCompat;
import androidx.core.view.MotionEventCompat;
import androidx.core.view.NestedScrollingChild;
import androidx.core.view.NestedScrollingChildHelper;
import androidx.core.view.NestedScrollingParent;
import androidx.core.view.NestedScrollingParentHelper;
import androidx.core.view.ScrollingView;
import androidx.core.view.VelocityTrackerCompat;
import androidx.core.view.ViewCompat;
import androidx.core.view.accessibility.AccessibilityEventCompat;
import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
import androidx.core.view.accessibility.AccessibilityRecordCompat;
import androidx.core.widget.EdgeEffectCompat;
import androidx.core.widget.ScrollerCompat;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.FocusFinder;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.accessibility.AccessibilityEvent;
import android.view.animation.AnimationUtils;
import android.widget.FrameLayout;
import android.widget.ScrollView;

import java.util.List;

/**
 * NestedScrollView is just like {@link android.widget.ScrollView}, but it supports acting
 * as both a nested scrolling parent and child on both new and old versions of Android.
 * Nested scrolling is enabled by default.
 */
public class ApptentiveNestedScrollView extends FrameLayout implements NestedScrollingParent,
		NestedScrollingChild, ScrollingView {
	static final int ANIMATED_SCROLL_GAP = 250;

	static final float MAX_SCROLL_FACTOR = 0.5f;

	private static final String TAG = "NestedScrollView";

	/**
	 * Interface definition for a callback to be invoked when the scroll
	 * X or Y positions of a view change.
	 *
	 * <p>This version of the interface works on all versions of Android, back to API v4.</p>
	 *
	 * @see #setOnScrollChangeListener(OnScrollChangeListener)
	 */
	public interface OnScrollChangeListener {
		/**
		 * Called when the scroll position of a view changes.
		 *
		 * @param v The view whose scroll position has changed.
		 * @param scrollX Current horizontal scroll origin.
		 * @param scrollY Current vertical scroll origin.
		 * @param oldScrollX Previous horizontal scroll origin.
		 * @param oldScrollY Previous vertical scroll origin.
		 */
		void onScrollChange(ApptentiveNestedScrollView v, int scrollX, int scrollY,
												int oldScrollX, int oldScrollY);
	}

	private long mLastScroll;

	private final Rect mTempRect = new Rect();
	private ScrollerCompat mScroller;
	private EdgeEffectCompat mEdgeGlowTop;
	private EdgeEffectCompat mEdgeGlowBottom;

	/**
	 * Position of the last motion event.
	 */
	private int mLastMotionY;

	/**
	 * True when the layout has changed but the traversal has not come through yet.
	 * Ideally the view hierarchy would keep track of this for us.
	 */
	private boolean mIsLayoutDirty = true;
	private boolean mIsLaidOut = false;

	/**
	 * The child to give focus to in the event that a child has requested focus while the
	 * layout is dirty. This prevents the scroll from being wrong if the child has not been
	 * laid out before requesting focus.
	 */
	private View mChildToScrollTo = null;

	/**
	 * True if the user is currently dragging this ScrollView around. This is
	 * not the same as 'is being flinged', which can be checked by
	 * mScroller.isFinished() (flinging begins when the user lifts his finger).
	 */
	private boolean mIsBeingDragged = false;

	/**
	 * Determines speed during touch scrolling
	 */
	private VelocityTracker mVelocityTracker;

	/**
	 * When set to true, the scroll view measure its child to make it fill the currently
	 * visible area.
	 */
	private boolean mFillViewport;

	/**
	 * Whether arrow scrolling is animated.
	 */
	private boolean mSmoothScrollingEnabled = true;

	private int mTouchSlop;
	private int mMinimumVelocity;
	private int mMaximumVelocity;

	/**
	 * ID of the active pointer. This is used to retain consistency during
	 * drags/flings if multiple pointers are used.
	 */
	private int mActivePointerId = INVALID_POINTER;

	/**
	 * Used during scrolling to retrieve the new offset within the window.
	 */
	private final int[] mScrollOffset = new int[2];
	private final int[] mScrollConsumed = new int[2];
	private int mNestedYOffset;

	/**
	 * Sentinel value for no current active pointer.
	 * Used by {@link #mActivePointerId}.
	 */
	private static final int INVALID_POINTER = -1;

	private SavedState mSavedState;

	private static final AccessibilityDelegate ACCESSIBILITY_DELEGATE = new AccessibilityDelegate();

	private static final int[] SCROLLVIEW_STYLEABLE = new int[] {
			android.R.attr.fillViewport
	};

	private final NestedScrollingParentHelper mParentHelper;
	private final NestedScrollingChildHelper mChildHelper;

	private float mVerticalScrollFactor;

	private OnScrollChangeListener mOnScrollChangeListener;

	public ApptentiveNestedScrollView(Context context) {
		this(context, null);
	}

	public ApptentiveNestedScrollView(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public ApptentiveNestedScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
		super(context, attrs, defStyleAttr);
		initScrollView();

		final TypedArray a = context.obtainStyledAttributes(
				attrs, SCROLLVIEW_STYLEABLE, defStyleAttr, 0);

		setFillViewport(a.getBoolean(0, false));

		a.recycle();

		mParentHelper = new NestedScrollingParentHelper(this);
		mChildHelper = new NestedScrollingChildHelper(this);

		// ...because why else would you be using this widget?
		setNestedScrollingEnabled(true);

		ViewCompat.setAccessibilityDelegate(this, ACCESSIBILITY_DELEGATE);
	}

	// NestedScrollingChild

	@Override
	public void setNestedScrollingEnabled(boolean enabled) {
		mChildHelper.setNestedScrollingEnabled(enabled);
	}

	@Override
	public boolean isNestedScrollingEnabled() {
		return mChildHelper.isNestedScrollingEnabled();
	}

	@Override
	public boolean startNestedScroll(int axes) {
		return mChildHelper.startNestedScroll(axes);
	}

	@Override
	public void stopNestedScroll() {
		mChildHelper.stopNestedScroll();
	}

	@Override
	public boolean hasNestedScrollingParent() {
		return mChildHelper.hasNestedScrollingParent();
	}

	@Override
	public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed,
																			int dyUnconsumed, int[] offsetInWindow) {
		return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed,
				offsetInWindow);
	}

	@Override
	public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) {
		return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow);
	}

	@Override
	public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) {
		return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed);
	}

	@Override
	public boolean dispatchNestedPreFling(float velocityX, float velocityY) {
		return mChildHelper.dispatchNestedPreFling(velocityX, velocityY);
	}

	// NestedScrollingParent

	@Override
	public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
		return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
	}

	@Override
	public void onNestedScrollAccepted(View child, View target, int nestedScrollAxes) {
		mParentHelper.onNestedScrollAccepted(child, target, nestedScrollAxes);
		startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL);
	}

	@Override
	public void onStopNestedScroll(View target) {
		mParentHelper.onStopNestedScroll(target);
		stopNestedScroll();
	}

	@Override
	public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed,
														 int dyUnconsumed) {
		final int oldScrollY = getScrollY();
		scrollBy(0, dyUnconsumed);
		final int myConsumed = getScrollY() - oldScrollY;
		final int myUnconsumed = dyUnconsumed - myConsumed;
		dispatchNestedScroll(0, myConsumed, 0, myUnconsumed, null);
	}

	@Override
	public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) {
		// Do nothing
	}

	@Override
	public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) {
		if (!consumed) {
			flingWithNestedDispatch((int) velocityY);
			return true;
		}
		return false;
	}

	@Override
	public boolean onNestedPreFling(View target, float velocityX, float velocityY) {
		// Do nothing
		return false;
	}

	@Override
	public int getNestedScrollAxes() {
		return mParentHelper.getNestedScrollAxes();
	}

	// ScrollView import

	public boolean shouldDelayChildPressedState() {
		return true;
	}

	@Override
	protected float getTopFadingEdgeStrength() {
		if (getChildCount() == 0) {
			return 0.0f;
		}

		final int length = getVerticalFadingEdgeLength();
		final int scrollY = getScrollY();
		if (scrollY < length) {
			return scrollY / (float) length;
		}

		return 1.0f;
	}

	@Override
	protected float getBottomFadingEdgeStrength() {
		if (getChildCount() == 0) {
			return 0.0f;
		}

		final int length = getVerticalFadingEdgeLength();
		final int bottomEdge = getHeight() - getPaddingBottom();
		final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge;
		if (span < length) {
			return span / (float) length;
		}

		return 1.0f;
	}

	/**
	 * @return The maximum amount this scroll view will scroll in response to
	 *   an arrow event.
	 */
	public int getMaxScrollAmount() {
		return (int) (MAX_SCROLL_FACTOR * getHeight());
	}

	private void initScrollView() {
		//mScroller = new ScrollerCompat(getContext(), null);
		mScroller = ScrollerCompat.create(getContext(), null);
		setFocusable(true);
		setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
		setWillNotDraw(false);
		final ViewConfiguration configuration = ViewConfiguration.get(getContext());
		mTouchSlop = configuration.getScaledTouchSlop();
		mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
		mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
	}

	@Override
	public void addView(View child) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child);
	}

	@Override
	public void addView(View child, int index) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child, index);
	}

	@Override
	public void addView(View child, ViewGroup.LayoutParams params) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child, params);
	}

	@Override
	public void addView(View child, int index, ViewGroup.LayoutParams params) {
		if (getChildCount() > 0) {
			throw new IllegalStateException("ScrollView can host only one direct child");
		}

		super.addView(child, index, params);
	}

	/**
	 * Register a callback to be invoked when the scroll X or Y positions of
	 * this view change.
	 * <p>This version of the method works on all versions of Android, back to API v4.</p>
	 *
	 * @param l The listener to notify when the scroll X or Y position changes.
	 * @see android.view.View#getScrollX()
	 * @see android.view.View#getScrollY()
	 */
	public void setOnScrollChangeListener(OnScrollChangeListener l) {
		mOnScrollChangeListener = l;
	}

	/**
	 * @return Returns true this ScrollView can be scrolled
	 */
	private boolean canScroll() {
		View child = getChildAt(0);
		if (child != null) {
			int childHeight = child.getHeight();
			return getHeight() < childHeight + getPaddingTop() + getPaddingBottom();
		}
		return false;
	}

	/**
	 * Indicates whether this ScrollView's content is stretched to fill the viewport.
	 *
	 * @return True if the content fills the viewport, false otherwise.
	 *
	 * @attr ref android.R.styleable#ScrollView_fillViewport
	 */
	public boolean isFillViewport() {
		return mFillViewport;
	}

	/**
	 * Indicates this ScrollView whether it should stretch its content height to fill
	 * the viewport or not.
	 *
	 * @param fillViewport True to stretch the content's height to the viewport's
	 *        boundaries, false otherwise.
	 *
	 * @attr ref android.R.styleable#ScrollView_fillViewport
	 */
	public void setFillViewport(boolean fillViewport) {
		if (fillViewport != mFillViewport) {
			mFillViewport = fillViewport;
			requestLayout();
		}
	}

	/**
	 * @return Whether arrow scrolling will animate its transition.
	 */
	public boolean isSmoothScrollingEnabled() {
		return mSmoothScrollingEnabled;
	}

	/**
	 * Set whether arrow scrolling will animate its transition.
	 * @param smoothScrollingEnabled whether arrow scrolling will animate its transition
	 */
	public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {
		mSmoothScrollingEnabled = smoothScrollingEnabled;
	}

	@Override
	protected void onScrollChanged(int l, int t, int oldl, int oldt) {
		super.onScrollChanged(l, t, oldl, oldt);

		if (mOnScrollChangeListener != null) {
			mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt);
		}
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);

		if (!mFillViewport) {
			return;
		}

		final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
		if (heightMode == MeasureSpec.UNSPECIFIED) {
			return;
		}

		if (getChildCount() > 0) {
			final View child = getChildAt(0);
			int height = getMeasuredHeight();
			if (child.getMeasuredHeight() < height) {
				final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams();

				int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
						getPaddingLeft() + getPaddingRight(), lp.width);
				height -= getPaddingTop();
				height -= getPaddingBottom();
				int childHeightMeasureSpec =
						MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);

				child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
			}
		}
	}

	@Override
	public boolean dispatchKeyEvent(KeyEvent event) {
		// Let the focused view and/or our descendants get the key first
		return super.dispatchKeyEvent(event) || executeKeyEvent(event);
	}

	/**
	 * You can call this function yourself to have the scroll view perform
	 * scrolling from a key event, just as if the event had been dispatched to
	 * it by the view hierarchy.
	 *
	 * @param event The key event to execute.
	 * @return Return true if the event was handled, else false.
	 */
	public boolean executeKeyEvent(KeyEvent event) {
		mTempRect.setEmpty();

		if (!canScroll()) {
			if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) {
				View currentFocused = findFocus();
				if (currentFocused == this) currentFocused = null;
				View nextFocused = FocusFinder.getInstance().findNextFocus(this,
						currentFocused, View.FOCUS_DOWN);
				return nextFocused != null
						&& nextFocused != this
						&& nextFocused.requestFocus(View.FOCUS_DOWN);
			}
			return false;
		}

		boolean handled = false;
		if (event.getAction() == KeyEvent.ACTION_DOWN) {
			switch (event.getKeyCode()) {
				case KeyEvent.KEYCODE_DPAD_UP:
					if (!event.isAltPressed()) {
						handled = arrowScroll(View.FOCUS_UP);
					} else {
						handled = fullScroll(View.FOCUS_UP);
					}
					break;
				case KeyEvent.KEYCODE_DPAD_DOWN:
					if (!event.isAltPressed()) {
						handled = arrowScroll(View.FOCUS_DOWN);
					} else {
						handled = fullScroll(View.FOCUS_DOWN);
					}
					break;
				case KeyEvent.KEYCODE_SPACE:
					pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN);
					break;
			}
		}

		return handled;
	}

	private boolean inChild(int x, int y) {
		if (getChildCount() > 0) {
			final int scrollY = getScrollY();
			final View child = getChildAt(0);
			return !(y < child.getTop() - scrollY
					|| y >= child.getBottom() - scrollY
					|| x < child.getLeft()
					|| x >= child.getRight());
		}
		return false;
	}

	private void initOrResetVelocityTracker() {
		if (mVelocityTracker == null) {
			mVelocityTracker = VelocityTracker.obtain();
		} else {
			mVelocityTracker.clear();
		}
	}

	private void initVelocityTrackerIfNotExists() {
		if (mVelocityTracker == null) {
			mVelocityTracker = VelocityTracker.obtain();
		}
	}

	private void recycleVelocityTracker() {
		if (mVelocityTracker != null) {
			mVelocityTracker.recycle();
			mVelocityTracker = null;
		}
	}

	@Override
	public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
		if (disallowIntercept) {
			recycleVelocityTracker();
		}
		super.requestDisallowInterceptTouchEvent(disallowIntercept);
	}


	@Override
	public boolean onInterceptTouchEvent(MotionEvent ev) {
        /*
         * This method JUST determines whether we want to intercept the motion.
         * If we return true, onMotionEvent will be called and we do the actual
         * scrolling there.
         */

        /*
        * Shortcut the most recurring case: the user is in the dragging
        * state and he is moving his finger.  We want to intercept this
        * motion.
        */
		final int action = ev.getAction();
		if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) {
			return true;
		}

		switch (action & MotionEventCompat.ACTION_MASK) {
			case MotionEvent.ACTION_MOVE: {
                /*
                 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
                 * whether the user has moved far enough from his original down touch.
                 */

                /*
                * Locally do absolute value. mLastMotionY is set to the y value
                * of the down event.
                */
				final int activePointerId = mActivePointerId;
				if (activePointerId == INVALID_POINTER) {
					// If we don't have a valid id, the touch down wasn't on content.
					break;
				}

				final int pointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId);
				if (pointerIndex == -1) {
					Log.e(TAG, "Invalid pointerId=" + activePointerId
							+ " in onInterceptTouchEvent");
					break;
				}

				final int y = (int) MotionEventCompat.getY(ev, pointerIndex);
				final int yDiff = Math.abs(y - mLastMotionY);
				if (yDiff > mTouchSlop
						&& (getNestedScrollAxes() & ViewCompat.SCROLL_AXIS_VERTICAL) == 0) {
					mIsBeingDragged = true;
					mLastMotionY = y;
					initVelocityTrackerIfNotExists();
					mVelocityTracker.addMovement(ev);
					mNestedYOffset = 0;
					final ViewParent parent = getParent();
					if (parent != null) {
						parent.requestDisallowInterceptTouchEvent(true);
					}
				}
				break;
			}

			case MotionEvent.ACTION_DOWN: {
				final int y = (int) ev.getY();
				if (!inChild((int) ev.getX(), y)) {
					mIsBeingDragged = false;
					recycleVelocityTracker();
					break;
				}

                /*
                 * Remember location of down touch.
                 * ACTION_DOWN always refers to pointer index 0.
                 */
				mLastMotionY = y;
				mActivePointerId = MotionEventCompat.getPointerId(ev, 0);

				initOrResetVelocityTracker();
				mVelocityTracker.addMovement(ev);
                /*
                * If being flinged and user touches the screen, initiate drag;
                * otherwise don't.  mScroller.isFinished should be false when
                * being flinged.
                */
				//mIsBeingDragged = !mScroller.isFinished();
				mIsBeingDragged = false;
				startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL);
				break;
			}

			case MotionEvent.ACTION_CANCEL:
			case MotionEvent.ACTION_UP:
                /* Release the drag */
				mIsBeingDragged = false;
				mActivePointerId = INVALID_POINTER;
				recycleVelocityTracker();
				if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) {
					ViewCompat.postInvalidateOnAnimation(this);
				}
				stopNestedScroll();
				break;
			case MotionEventCompat.ACTION_POINTER_UP:
				onSecondaryPointerUp(ev);
				break;
		}

        /*
        * The only time we want to intercept motion events is if we are in the
        * drag mode.
        */
		return mIsBeingDragged;
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
		initVelocityTrackerIfNotExists();

		MotionEvent vtev = MotionEvent.obtain(ev);

		final int actionMasked = MotionEventCompat.getActionMasked(ev);

		if (actionMasked == MotionEvent.ACTION_DOWN) {
			mNestedYOffset = 0;
		}
		vtev.offsetLocation(0, mNestedYOffset);

		switch (actionMasked) {
			case MotionEvent.ACTION_DOWN: {
				if (getChildCount() == 0) {
					return false;
				}
				if ((mIsBeingDragged = !mScroller.isFinished())) {
					final ViewParent parent = getParent();
					if (parent != null) {
						parent.requestDisallowInterceptTouchEvent(true);
					}
				}

                /*
                 * If being flinged and user touches, stop the fling. isFinished
                 * will be false if being flinged.
                 */
				if (!mScroller.isFinished()) {
					mScroller.abortAnimation();
				}

				// Remember where the motion event started
				mLastMotionY = (int) ev.getY();
				mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
				startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL);
				break;
			}
			case MotionEvent.ACTION_MOVE:
				final int activePointerIndex = MotionEventCompat.findPointerIndex(ev,
						mActivePointerId);
				if (activePointerIndex == -1) {
					Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent");
					break;
				}

				final int y = (int) MotionEventCompat.getY(ev, activePointerIndex);
				int deltaY = mLastMotionY - y;
				if (dispatchNestedPreScroll(0, deltaY, mScrollConsumed, mScrollOffset)) {
					deltaY -= mScrollConsumed[1];
					vtev.offsetLocation(0, mScrollOffset[1]);
					mNestedYOffset += mScrollOffset[1];
				}
				if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) {
					final ViewParent parent = getParent();
					if (parent != null) {
						parent.requestDisallowInterceptTouchEvent(true);
					}
					mIsBeingDragged = true;
					if (deltaY > 0) {
						deltaY -= mTouchSlop;
					} else {
						deltaY += mTouchSlop;
					}
				}
				if (mIsBeingDragged) {
					// Scroll to follow the motion event
					mLastMotionY = y - mScrollOffset[1];

					final int oldY = getScrollY();
					final int range = getScrollRange();
					final int overscrollMode = ViewCompat.getOverScrollMode(this);
					boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS ||
							(overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS &&
									range > 0);

					// Calling overScrollByCompat will call onOverScrolled, which
					// calls onScrollChanged if applicable.
					if (overScrollByCompat(0, deltaY, 0, getScrollY(), 0, range, 0,
							0, true) && !hasNestedScrollingParent()) {
						// Break our velocity if we hit a scroll barrier.
						mVelocityTracker.clear();
					}

					final int scrolledDeltaY = getScrollY() - oldY;
					final int unconsumedY = deltaY - scrolledDeltaY;
					if (dispatchNestedScroll(0, scrolledDeltaY, 0, unconsumedY, mScrollOffset)) {
						mLastMotionY -= mScrollOffset[1];
						vtev.offsetLocation(0, mScrollOffset[1]);
						mNestedYOffset += mScrollOffset[1];
					} else if (canOverscroll) {
						ensureGlows();
						final int pulledToY = oldY + deltaY;
						if (pulledToY < 0) {
							mEdgeGlowTop.onPull((float) deltaY / getHeight(),
									MotionEventCompat.getX(ev, activePointerIndex) / getWidth());
							if (!mEdgeGlowBottom.isFinished()) {
								mEdgeGlowBottom.onRelease();
							}
						} else if (pulledToY > range) {
							mEdgeGlowBottom.onPull((float) deltaY / getHeight(),
									1.f - MotionEventCompat.getX(ev, activePointerIndex)
											/ getWidth());
							if (!mEdgeGlowTop.isFinished()) {
								mEdgeGlowTop.onRelease();
							}
						}
						if (mEdgeGlowTop != null
								&& (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) {
							ViewCompat.postInvalidateOnAnimation(this);
						}
					}
				}
				break;
			case MotionEvent.ACTION_UP:
				if (mIsBeingDragged) {
					final VelocityTracker velocityTracker = mVelocityTracker;
					velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
					int initialVelocity = (int) VelocityTrackerCompat.getYVelocity(velocityTracker,
							mActivePointerId);

					if ((Math.abs(initialVelocity) > mMinimumVelocity)) {
						flingWithNestedDispatch(-initialVelocity);
					} else if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0,
							getScrollRange())) {
						ViewCompat.postInvalidateOnAnimation(this);
					}
				}
				mActivePointerId = INVALID_POINTER;
				endDrag();
				break;
			case MotionEvent.ACTION_CANCEL:
				if (mIsBeingDragged && getChildCount() > 0) {
					if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0,
							getScrollRange())) {
						ViewCompat.postInvalidateOnAnimation(this);
					}
				}
				mActivePointerId = INVALID_POINTER;
				endDrag();
				break;
			case MotionEventCompat.ACTION_POINTER_DOWN: {
				final int index = MotionEventCompat.getActionIndex(ev);
				mLastMotionY = (int) MotionEventCompat.getY(ev, index);
				mActivePointerId = MotionEventCompat.getPointerId(ev, index);
				break;
			}
			case MotionEventCompat.ACTION_POINTER_UP:
				onSecondaryPointerUp(ev);
				mLastMotionY = (int) MotionEventCompat.getY(ev,
						MotionEventCompat.findPointerIndex(ev, mActivePointerId));
				break;
		}

		if (mVelocityTracker != null) {
			mVelocityTracker.addMovement(vtev);
		}
		vtev.recycle();
		return true;
	}

	private void onSecondaryPointerUp(MotionEvent ev) {
		final int pointerIndex = (ev.getAction() & MotionEventCompat.ACTION_POINTER_INDEX_MASK) >>
				MotionEventCompat.ACTION_POINTER_INDEX_SHIFT;
		final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
		if (pointerId == mActivePointerId) {
			// This was our active pointer going up. Choose a new
			// active pointer and adjust accordingly.
			// TODO: Make this decision more intelligent.
			final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
			mLastMotionY = (int) MotionEventCompat.getY(ev, newPointerIndex);
			mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex);
			if (mVelocityTracker != null) {
				mVelocityTracker.clear();
			}
		}
	}

	public boolean onGenericMotionEvent(MotionEvent event) {
		if ((MotionEventCompat.getSource(event) & InputDeviceCompat.SOURCE_CLASS_POINTER) != 0) {
			switch (event.getAction()) {
				case MotionEventCompat.ACTION_SCROLL: {
					if (!mIsBeingDragged) {
						final float vscroll = MotionEventCompat.getAxisValue(event,
								MotionEventCompat.AXIS_VSCROLL);
						if (vscroll != 0) {
							final int delta = (int) (vscroll * getVerticalScrollFactorCompat());
							final int range = getScrollRange();
							int oldScrollY = getScrollY();
							int newScrollY = oldScrollY - delta;
							if (newScrollY < 0) {
								newScrollY = 0;
							} else if (newScrollY > range) {
								newScrollY = range;
							}
							if (newScrollY != oldScrollY) {
								super.scrollTo(getScrollX(), newScrollY);
								return true;
							}
						}
					}
				}
			}
		}
		return false;
	}

	private float getVerticalScrollFactorCompat() {
		if (mVerticalScrollFactor == 0) {
			TypedValue outValue = new TypedValue();
			final Context context = getContext();
			if (!context.getTheme().resolveAttribute(
					android.R.attr.listPreferredItemHeight, outValue, true)) {
				throw new IllegalStateException(
						"Expected theme to define listPreferredItemHeight.");
			}
			mVerticalScrollFactor = outValue.getDimension(
					context.getResources().getDisplayMetrics());
		}
		return mVerticalScrollFactor;
	}

	protected void onOverScrolled(int scrollX, int scrollY,
																boolean clampedX, boolean clampedY) {
		super.scrollTo(scrollX, scrollY);
	}

	boolean overScrollByCompat(int deltaX, int deltaY,
														 int scrollX, int scrollY,
														 int scrollRangeX, int scrollRangeY,
														 int maxOverScrollX, int maxOverScrollY,
														 boolean isTouchEvent) {
		final int overScrollMode = ViewCompat.getOverScrollMode(this);
		final boolean canScrollHorizontal =
				computeHorizontalScrollRange() > computeHorizontalScrollExtent();
		final boolean canScrollVertical =
				computeVerticalScrollRange() > computeVerticalScrollExtent();
		final boolean overScrollHorizontal = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS ||
				(overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal);
		final boolean overScrollVertical = overScrollMode == ViewCompat.OVER_SCROLL_ALWAYS ||
				(overScrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical);

		int newScrollX = scrollX + deltaX;
		if (!overScrollHorizontal) {
			maxOverScrollX = 0;
		}

		int newScrollY = scrollY + deltaY;
		if (!overScrollVertical) {
			maxOverScrollY = 0;
		}

		// Clamp values if at the limits and record
		final int left = -maxOverScrollX;
		final int right = maxOverScrollX + scrollRangeX;
		final int top = -maxOverScrollY;
		final int bottom = maxOverScrollY + scrollRangeY;

		boolean clampedX = false;
		if (newScrollX > right) {
			newScrollX = right;
			clampedX = true;
		} else if (newScrollX < left) {
			newScrollX = left;
			clampedX = true;
		}

		boolean clampedY = false;
		if (newScrollY > bottom) {
			newScrollY = bottom;
			clampedY = true;
		} else if (newScrollY < top) {
			newScrollY = top;
			clampedY = true;
		}

		if (clampedY) {
			mScroller.springBack(newScrollX, newScrollY, 0, 0, 0, getScrollRange());
		}

		onOverScrolled(newScrollX, newScrollY, clampedX, clampedY);

		return clampedX || clampedY;
	}

	private int getScrollRange() {
		int scrollRange = 0;
		if (getChildCount() > 0) {
			View child = getChildAt(0);
			scrollRange = Math.max(0,
					child.getHeight() - (getHeight() - getPaddingBottom() - getPaddingTop()));
		}
		return scrollRange;
	}

	/**
	 * <p>
	 * Finds the next focusable component that fits in the specified bounds.
	 * </p>
	 *
	 * @param topFocus look for a candidate is the one at the top of the bounds
	 *                 if topFocus is true, or at the bottom of the bounds if topFocus is
	 *                 false
	 * @param top      the top offset of the bounds in which a focusable must be
	 *                 found
	 * @param bottom   the bottom offset of the bounds in which a focusable must
	 *                 be found
	 * @return the next focusable component in the bounds or null if none can
	 *         be found
	 */
	private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) {

		List<View> focusables = getFocusables(View.FOCUS_FORWARD);
		View focusCandidate = null;

        /*
         * A fully contained focusable is one where its top is below the bound's
         * top, and its bottom is above the bound's bottom. A partially
         * contained focusable is one where some part of it is within the
         * bounds, but it also has some part that is not within bounds.  A fully contained
         * focusable is preferred to a partially contained focusable.
         */
		boolean foundFullyContainedFocusable = false;

		int count = focusables.size();
		for (int i = 0; i < count; i++) {
			View view = focusables.get(i);
			int viewTop = view.getTop();
			int viewBottom = view.getBottom();

			if (top < viewBottom && viewTop < bottom) {
                /*
                 * the focusable is in the target area, it is a candidate for
                 * focusing
                 */

				final boolean viewIsFullyContained = (top < viewTop) &&
						(viewBottom < bottom);

				if (focusCandidate == null) {
                    /* No candidate, take this one */
					focusCandidate = view;
					foundFullyContainedFocusable = viewIsFullyContained;
				} else {
					final boolean viewIsCloserToBoundary =
							(topFocus && viewTop < focusCandidate.getTop()) ||
									(!topFocus && viewBottom > focusCandidate
											.getBottom());

					if (foundFullyContainedFocusable) {
						if (viewIsFullyContained && viewIsCloserToBoundary) {
                            /*
                             * We're dealing with only fully contained views, so
                             * it has to be closer to the boundary to beat our
                             * candidate
                             */
							focusCandidate = view;
						}
					} else {
						if (viewIsFullyContained) {
                            /* Any fully contained view beats a partially contained view */
							focusCandidate = view;
							foundFullyContainedFocusable = true;
						} else if (viewIsCloserToBoundary) {
                            /*
                             * Partially contained view beats another partially
                             * contained view if it's closer
                             */
							focusCandidate = view;
						}
					}
				}
			}
		}

		return focusCandidate;
	}

	/**
	 * <p>Handles scrolling in response to a "page up/down" shortcut press. This
	 * method will scroll the view by one page up or down and give the focus
	 * to the topmost/bottommost component in the new visible area. If no
	 * component is a good candidate for focus, this scrollview reclaims the
	 * focus.</p>
	 *
	 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
	 *                  to go one page up or
	 *                  {@link android.view.View#FOCUS_DOWN} to go one page down
	 * @return true if the key event is consumed by this method, false otherwise
	 */
	public boolean pageScroll(int direction) {
		boolean down = direction == View.FOCUS_DOWN;
		int height = getHeight();

		if (down) {
			mTempRect.top = getScrollY() + height;
			int count = getChildCount();
			if (count > 0) {
				View view = getChildAt(count - 1);
				if (mTempRect.top + height > view.getBottom()) {
					mTempRect.top = view.getBottom() - height;
				}
			}
		} else {
			mTempRect.top = getScrollY() - height;
			if (mTempRect.top < 0) {
				mTempRect.top = 0;
			}
		}
		mTempRect.bottom = mTempRect.top + height;

		return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
	}

	/**
	 * <p>Handles scrolling in response to a "home/end" shortcut press. This
	 * method will scroll the view to the top or bottom and give the focus
	 * to the topmost/bottommost component in the new visible area. If no
	 * component is a good candidate for focus, this scrollview reclaims the
	 * focus.</p>
	 *
	 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
	 *                  to go the top of the view or
	 *                  {@link android.view.View#FOCUS_DOWN} to go the bottom
	 * @return true if the key event is consumed by this method, false otherwise
	 */
	public boolean fullScroll(int direction) {
		boolean down = direction == View.FOCUS_DOWN;
		int height = getHeight();

		mTempRect.top = 0;
		mTempRect.bottom = height;

		if (down) {
			int count = getChildCount();
			if (count > 0) {
				View view = getChildAt(count - 1);
				mTempRect.bottom = view.getBottom() + getPaddingBottom();
				mTempRect.top = mTempRect.bottom - height;
			}
		}

		return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
	}

	/**
	 * <p>Scrolls the view to make the area defined by <code>top</code> and
	 * <code>bottom</code> visible. This method attempts to give the focus
	 * to a component visible in this area. If no component can be focused in
	 * the new visible area, the focus is reclaimed by this ScrollView.</p>
	 *
	 * @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
	 *                  to go upward, {@link android.view.View#FOCUS_DOWN} to downward
	 * @param top       the top offset of the new area to be made visible
	 * @param bottom    the bottom offset of the new area to be made visible
	 * @return true if the key event is consumed by this method, false otherwise
	 */
	private boolean scrollAndFocus(int direction, int top, int bottom) {
		boolean handled = true;

		int height = getHeight();
		int containerTop = getScrollY();
		int containerBottom = containerTop + height;
		boolean up = direction == View.FOCUS_UP;

		View newFocused = findFocusableViewInBounds(up, top, bottom);
		if (newFocused == null) {
			newFocused = this;
		}

		if (top >= containerTop && bottom <= containerBottom) {
			handled = false;
		} else {
			int delta = up ? (top - containerTop) : (bottom - containerBottom);
			doScrollY(delta);
		}

		if (newFocused != findFocus()) newFocused.requestFocus(direction);

		return handled;
	}

	/**
	 * Handle scrolling in response to an up or down arrow click.
	 *
	 * @param direction The direction corresponding to the arrow key that was
	 *                  pressed
	 * @return True if we consumed the event, false otherwise
	 */
	public boolean arrowScroll(int direction) {

		View currentFocused = findFocus();
		if (currentFocused == this) currentFocused = null;

		View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);

		final int maxJump = getMaxScrollAmount();

		if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) {
			nextFocused.getDrawingRect(mTempRect);
			offsetDescendantRectToMyCoords(nextFocused, mTempRect);
			int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
			doScrollY(scrollDelta);
			nextFocused.requestFocus(direction);
		} else {
			// no new focus
			int scrollDelta = maxJump;

			if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) {
				scrollDelta = getScrollY();
			} else if (direction == View.FOCUS_DOWN) {
				if (getChildCount() > 0) {
					int daBottom = getChildAt(0).getBottom();
					int screenBottom = getScrollY() + getHeight() - getPaddingBottom();
					if (daBottom - screenBottom < maxJump) {
						scrollDelta = daBottom - screenBottom;
					}
				}
			}
			if (scrollDelta == 0) {
				return false;
			}
			doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);
		}

		if (currentFocused != null && currentFocused.isFocused()
				&& isOffScreen(currentFocused)) {
			// previously focused item still has focus and is off screen, give
			// it up (take it back to ourselves)
			// (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are
			// sure to
			// get it)
			final int descendantFocusability = getDescendantFocusability();  // save
			setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);
			requestFocus();
			setDescendantFocusability(descendantFocusability);  // restore
		}
		return true;
	}

	/**
	 * @return whether the descendant of this scroll view is scrolled off
	 *  screen.
	 */
	private boolean isOffScreen(View descendant) {
		return !isWithinDeltaOfScreen(descendant, 0, getHeight());
	}

	/**
	 * @return whether the descendant of this scroll view is within delta
	 *  pixels of being on the screen.
	 */
	private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) {
		descendant.getDrawingRect(mTempRect);
		offsetDescendantRectToMyCoords(descendant, mTempRect);

		return (mTempRect.bottom + delta) >= getScrollY()
				&& (mTempRect.top - delta) <= (getScrollY() + height);
	}

	/**
	 * Smooth scroll by a Y delta
	 *
	 * @param delta the number of pixels to scroll by on the Y axis
	 */
	private void doScrollY(int delta) {
		if (delta != 0) {
			if (mSmoothScrollingEnabled) {
				smoothScrollBy(0, delta);
			} else {
				scrollBy(0, delta);
			}
		}
	}

	/**
	 * Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
	 *
	 * @param dx the number of pixels to scroll by on the X axis
	 * @param dy the number of pixels to scroll by on the Y axis
	 */
	public final void smoothScrollBy(int dx, int dy) {
		if (getChildCount() == 0) {
			// Nothing to do.
			return;
		}
		long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;
		if (duration > ANIMATED_SCROLL_GAP) {
			final int height = getHeight() - getPaddingBottom() - getPaddingTop();
			final int bottom = getChildAt(0).getHeight();
			final int maxY = Math.max(0, bottom - height);
			final int scrollY = getScrollY();
			dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY;

			mScroller.startScroll(getScrollX(), scrollY, 0, dy);
			ViewCompat.postInvalidateOnAnimation(this);
		} else {
			if (!mScroller.isFinished()) {
				mScroller.abortAnimation();
			}
			scrollBy(dx, dy);
		}
		mLastScroll = AnimationUtils.currentAnimationTimeMillis();
	}

	/**
	 * Like {@link #scrollTo}, but scroll smoothly instead of immediately.
	 *
	 * @param x the position where to scroll on the X axis
	 * @param y the position where to scroll on the Y axis
	 */
	public final void smoothScrollTo(int x, int y) {
		smoothScrollBy(x - getScrollX(), y - getScrollY());
	}

	/**
	 * <p>The scroll range of a scroll view is the overall height of all of its
	 * children.</p>
	 * @hide
	 */
	@Override
	public int computeVerticalScrollRange() {
		final int count = getChildCount();
		final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop();
		if (count == 0) {
			return contentHeight;
		}

		int scrollRange = getChildAt(0).getBottom();
		final int scrollY = getScrollY();
		final int overscrollBottom = Math.max(0, scrollRange - contentHeight);
		if (scrollY < 0) {
			scrollRange -= scrollY;
		} else if (scrollY > overscrollBottom) {
			scrollRange += scrollY - overscrollBottom;
		}

		return scrollRange;
	}

	/** @hide */
	@Override
	public int computeVerticalScrollOffset() {
		return Math.max(0, super.computeVerticalScrollOffset());
	}

	/** @hide */
	@Override
	public int computeVerticalScrollExtent() {
		return super.computeVerticalScrollExtent();
	}

	/** @hide */
	@Override
	public int computeHorizontalScrollRange() {
		return super.computeHorizontalScrollRange();
	}

	/** @hide */
	@Override
	public int computeHorizontalScrollOffset() {
		return super.computeHorizontalScrollOffset();
	}

	/** @hide */
	@Override
	public int computeHorizontalScrollExtent() {
		return super.computeHorizontalScrollExtent();
	}

	@Override
	protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) {
		ViewGroup.LayoutParams lp = child.getLayoutParams();

		int childWidthMeasureSpec;
		int childHeightMeasureSpec;

		childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft()
				+ getPaddingRight(), lp.width);

		childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);

		child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
	}

	@Override
	protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,
																				 int parentHeightMeasureSpec, int heightUsed) {
		final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

		final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
				getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin
						+ widthUsed, lp.width);
		final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
				lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);

		child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
	}

	@Override
	public void computeScroll() {
		if (mScroller.computeScrollOffset()) {
			int oldX = getScrollX();
			int oldY = getScrollY();
			int x = mScroller.getCurrX();
			int y = mScroller.getCurrY();

			if (oldX != x || oldY != y) {
				final int range = getScrollRange();
				final int overscrollMode = ViewCompat.getOverScrollMode(this);
				final boolean canOverscroll = overscrollMode == ViewCompat.OVER_SCROLL_ALWAYS ||
						(overscrollMode == ViewCompat.OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);

				overScrollByCompat(x - oldX, y - oldY, oldX, oldY, 0, range,
						0, 0, false);

				if (canOverscroll) {
					ensureGlows();
					if (y <= 0 && oldY > 0) {
						mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity());
					} else if (y >= range && oldY < range) {
						mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity());
					}
				}
			}
		}
	}

	/**
	 * Scrolls the view to the given child.
	 *
	 * @param child the View to scroll to
	 */
	public void scrollToChild(View child) {
		child.getDrawingRect(mTempRect);

        /* Offset from child's local coordinates to ScrollView coordinates */
		offsetDescendantRectToMyCoords(child, mTempRect);

		int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);

		if (scrollDelta != 0) {
			scrollBy(0, scrollDelta);
		}
	}

	/**
	 * If rect is off screen, scroll just enough to get it (or at least the
	 * first screen size chunk of it) on screen.
	 *
	 * @param rect      The rectangle.
	 * @param immediate True to scroll immediately without animation
	 * @return true if scrolling was performed
	 */
	private boolean scrollToChildRect(Rect rect, boolean immediate) {
		final int delta = computeScrollDeltaToGetChildRectOnScreen(rect);
		final boolean scroll = delta != 0;
		if (scroll) {
			if (immediate) {
				scrollBy(0, delta);
			} else {
				smoothScrollBy(0, delta);
			}
		}
		return scroll;
	}

	/**
	 * Compute the amount to scroll in the Y direction in order to get
	 * a rectangle completely on the screen (or, if taller than the screen,
	 * at least the first screen size chunk of it).
	 *
	 * @param rect The rect.
	 * @return The scroll delta.
	 */
	protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
		if (getChildCount() == 0) return 0;

		int height = getHeight();
		int screenTop = getScrollY();
		int screenBottom = screenTop + height;

		int fadingEdge = getVerticalFadingEdgeLength();

		// leave room for top fading edge as long as rect isn't at very top
		if (rect.top > 0) {
			screenTop += fadingEdge;
		}

		// leave room for bottom fading edge as long as rect isn't at very bottom
		if (rect.bottom < getChildAt(0).getHeight()) {
			screenBottom -= fadingEdge;
		}

		int scrollYDelta = 0;

		if (rect.bottom > screenBottom && rect.top > screenTop) {
			// need to move down to get it in view: move down just enough so
			// that the entire rectangle is in view (or at least the first
			// screen size chunk).

			if (rect.height() > height) {
				// just enough to get screen size chunk on
				scrollYDelta += (rect.top - screenTop);
			} else {
				// get entire rect at bottom of screen
				scrollYDelta += (rect.bottom - screenBottom);
			}

			// make sure we aren't scrolling beyond the end of our content
			int bottom = getChildAt(0).getBottom();
			int distanceToBottom = bottom - screenBottom;
			scrollYDelta = Math.min(scrollYDelta, distanceToBottom);

		} else if (rect.top < screenTop && rect.bottom < screenBottom) {
			// need to move up to get it in view: move up just enough so that
			// entire rectangle is in view (or at least the first screen
			// size chunk of it).

			if (rect.height() > height) {
				// screen size chunk
				scrollYDelta -= (screenBottom - rect.bottom);
			} else {
				// entire rect at top
				scrollYDelta -= (screenTop - rect.top);
			}

			// make sure we aren't scrolling any further than the top our content
			scrollYDelta = Math.max(scrollYDelta, -getScrollY());
		}
		return scrollYDelta;
	}

	@Override
	public void requestChildFocus(View child, View focused) {
		if (!mIsLayoutDirty) {
			scrollToChild(focused);
		} else {
			// The child may not be laid out yet, we can't compute the scroll yet
			mChildToScrollTo = focused;
		}
		super.requestChildFocus(child, focused);
	}


	/**
	 * When looking for focus in children of a scroll view, need to be a little
	 * more careful not to give focus to something that is scrolled off screen.
	 *
	 * This is more expensive than the default {@link android.view.ViewGroup}
	 * implementation, otherwise this behavior might have been made the default.
	 */
	@Override
	protected boolean onRequestFocusInDescendants(int direction,
																								Rect previouslyFocusedRect) {

		// convert from forward / backward notation to up / down / left / right
		// (ugh).
		if (direction == View.FOCUS_FORWARD) {
			direction = View.FOCUS_DOWN;
		} else if (direction == View.FOCUS_BACKWARD) {
			direction = View.FOCUS_UP;
		}

		final View nextFocus = previouslyFocusedRect == null ?
				FocusFinder.getInstance().findNextFocus(this, null, direction) :
				FocusFinder.getInstance().findNextFocusFromRect(this,
						previouslyFocusedRect, direction);

		if (nextFocus == null) {
			return false;
		}

		if (isOffScreen(nextFocus)) {
			return false;
		}

		return nextFocus.requestFocus(direction, previouslyFocusedRect);
	}

	@Override
	public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
																							 boolean immediate) {
		// offset into coordinate space of this scroll view
		rectangle.offset(child.getLeft() - child.getScrollX(),
				child.getTop() - child.getScrollY());

		return scrollToChildRect(rectangle, immediate);
	}

	@Override
	public void requestLayout() {
		mIsLayoutDirty = true;
		super.requestLayout();
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		super.onLayout(changed, l, t, r, b);
		mIsLayoutDirty = false;
		// Give a child focus if it needs it
		if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) {
			scrollToChild(mChildToScrollTo);
		}
		mChildToScrollTo = null;

		if (!mIsLaidOut) {
			if (mSavedState != null) {
				scrollTo(getScrollX(), mSavedState.scrollPosition);
				mSavedState = null;
			} // mScrollY default value is "0"

			final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0;
			final int scrollRange = Math.max(0,
					childHeight - (b - t - getPaddingBottom() - getPaddingTop()));

			// Don't forget to clamp
			if (getScrollY() > scrollRange) {
				scrollTo(getScrollX(), scrollRange);
			} else if (getScrollY() < 0) {
				scrollTo(getScrollX(), 0);
			}
		}

		// Calling this with the present values causes it to re-claim them
		scrollTo(getScrollX(), getScrollY());
		mIsLaidOut = true;
	}

	@Override
	public void onAttachedToWindow() {
		mIsLaidOut = false;
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		super.onSizeChanged(w, h, oldw, oldh);

		View currentFocused = findFocus();
		if (null == currentFocused || this == currentFocused)
			return;

		// If the currently-focused view was visible on the screen when the
		// screen was at the old height, then scroll the screen to make that
		// view visible with the new screen height.
		if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) {
			currentFocused.getDrawingRect(mTempRect);
			offsetDescendantRectToMyCoords(currentFocused, mTempRect);
			int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
			doScrollY(scrollDelta);
		}
	}

	/**
	 * Return true if child is a descendant of parent, (or equal to the parent).
	 */
	private static boolean isViewDescendantOf(View child, View parent) {
		if (child == parent) {
			return true;
		}

		final ViewParent theParent = child.getParent();
		return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent);
	}

	/**
	 * Fling the scroll view
	 *
	 * @param velocityY The initial velocity in the Y direction. Positive
	 *                  numbers mean that the finger/cursor is moving down the screen,
	 *                  which means we want to scroll towards the top.
	 */
	public void fling(int velocityY) {
		if (getChildCount() > 0) {
			int height = getHeight() - getPaddingBottom() - getPaddingTop();
			int bottom = getChildAt(0).getHeight();

			mScroller.fling(getScrollX(), getScrollY(), 0, velocityY, 0, 0, 0,
					Math.max(0, bottom - height), 0, height/2);

			ViewCompat.postInvalidateOnAnimation(this);
		}
	}

	private void flingWithNestedDispatch(int velocityY) {
		final int scrollY = getScrollY();
		final boolean canFling = (scrollY > 0 || velocityY > 0) &&
				(scrollY < getScrollRange() || velocityY < 0);
		if (!dispatchNestedPreFling(0, velocityY)) {
			dispatchNestedFling(0, velocityY, canFling);
			if (canFling) {
				fling(velocityY);
			}
		}
	}

	private void endDrag() {
		mIsBeingDragged = false;

		recycleVelocityTracker();
		stopNestedScroll();

		if (mEdgeGlowTop != null) {
			mEdgeGlowTop.onRelease();
			mEdgeGlowBottom.onRelease();
		}
	}

	/**
	 * {@inheritDoc}
	 *
	 * <p>This version also clamps the scrolling to the bounds of our child.
	 */
	@Override
	public void scrollTo(int x, int y) {
		// we rely on the fact the View.scrollBy calls scrollTo.
		if (getChildCount() > 0) {
			View child = getChildAt(0);
			x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth());
			y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight());
			if (x != getScrollX() || y != getScrollY()) {
				super.scrollTo(x, y);
			}
		}
	}

	private void ensureGlows() {
		if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) {
			if (mEdgeGlowTop == null) {
				Context context = getContext();
				mEdgeGlowTop = new EdgeEffectCompat(context);
				mEdgeGlowBottom = new EdgeEffectCompat(context);
			}
		} else {
			mEdgeGlowTop = null;
			mEdgeGlowBottom = null;
		}
	}

	@Override
	public void draw(Canvas canvas) {
		super.draw(canvas);
		if (mEdgeGlowTop != null) {
			final int scrollY = getScrollY();
			if (!mEdgeGlowTop.isFinished()) {
				final int restoreCount = canvas.save();
				final int width = getWidth() - getPaddingLeft() - getPaddingRight();

				canvas.translate(getPaddingLeft(), Math.min(0, scrollY));
				mEdgeGlowTop.setSize(width, getHeight());
				if (mEdgeGlowTop.draw(canvas)) {
					ViewCompat.postInvalidateOnAnimation(this);
				}
				canvas.restoreToCount(restoreCount);
			}
			if (!mEdgeGlowBottom.isFinished()) {
				final int restoreCount = canvas.save();
				final int width = getWidth() - getPaddingLeft() - getPaddingRight();
				final int height = getHeight();

				canvas.translate(-width + getPaddingLeft(),
						Math.max(getScrollRange(), scrollY) + height);
				canvas.rotate(180, width, 0);
				mEdgeGlowBottom.setSize(width, height);
				if (mEdgeGlowBottom.draw(canvas)) {
					ViewCompat.postInvalidateOnAnimation(this);
				}
				canvas.restoreToCount(restoreCount);
			}
		}
	}

	private static int clamp(int n, int my, int child) {
		if (my >= child || n < 0) {
            /* my >= child is this case:
             *                    |--------------- me ---------------|
             *     |------ child ------|
             * or
             *     |--------------- me ---------------|
             *            |------ child ------|
             * or
             *     |--------------- me ---------------|
             *                                  |------ child ------|
             *
             * n < 0 is this case:
             *     |------ me ------|
             *                    |-------- child --------|
             *     |-- mScrollX --|
             */
			return 0;
		}
		if ((my+n) > child) {
            /* this case:
             *                    |------ me ------|
             *     |------ child ------|
             *     |-- mScrollX --|
             */
			return child-my;
		}
		return n;
	}

	@Override
	protected void onRestoreInstanceState(Parcelable state) {
		SavedState ss = (SavedState) state;
		super.onRestoreInstanceState(ss.getSuperState());
		mSavedState = ss;
		requestLayout();
	}

	@Override
	protected Parcelable onSaveInstanceState() {
		Parcelable superState = super.onSaveInstanceState();
		SavedState ss = new SavedState(superState);
		ss.scrollPosition = getScrollY();
		return ss;
	}

	static class SavedState extends BaseSavedState {
		public int scrollPosition;

		SavedState(Parcelable superState) {
			super(superState);
		}

		public SavedState(Parcel source) {
			super(source);
			scrollPosition = source.readInt();
		}

		@Override
		public void writeToParcel(Parcel dest, int flags) {
			super.writeToParcel(dest, flags);
			dest.writeInt(scrollPosition);
		}

		@Override
		public String toString() {
			return "HorizontalScrollView.SavedState{"
					+ Integer.toHexString(System.identityHashCode(this))
					+ " scrollPosition=" + scrollPosition + "}";
		}

		public static final Parcelable.Creator<SavedState> CREATOR
				= new Parcelable.Creator<SavedState>() {
			public SavedState createFromParcel(Parcel in) {
				return new SavedState(in);
			}

			public SavedState[] newArray(int size) {
				return new SavedState[size];
			}
		};
	}

	static class AccessibilityDelegate extends AccessibilityDelegateCompat {
		@Override
		public boolean performAccessibilityAction(View host, int action, Bundle arguments) {
			if (super.performAccessibilityAction(host, action, arguments)) {
				return true;
			}
			final ApptentiveNestedScrollView nsvHost = (ApptentiveNestedScrollView) host;
			if (!nsvHost.isEnabled()) {
				return false;
			}
			switch (action) {
				case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD: {
					final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom()
							- nsvHost.getPaddingTop();
					final int targetScrollY = Math.min(nsvHost.getScrollY() + viewportHeight,
							nsvHost.getScrollRange());
					if (targetScrollY != nsvHost.getScrollY()) {
						nsvHost.smoothScrollTo(0, targetScrollY);
						return true;
					}
				}
				return false;
				case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD: {
					final int viewportHeight = nsvHost.getHeight() - nsvHost.getPaddingBottom()
							- nsvHost.getPaddingTop();
					final int targetScrollY = Math.max(nsvHost.getScrollY() - viewportHeight, 0);
					if (targetScrollY != nsvHost.getScrollY()) {
						nsvHost.smoothScrollTo(0, targetScrollY);
						return true;
					}
				}
				return false;
			}
			return false;
		}

		@Override
		public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) {
			super.onInitializeAccessibilityNodeInfo(host, info);
			final ApptentiveNestedScrollView nsvHost = (ApptentiveNestedScrollView) host;
			info.setClassName(ScrollView.class.getName());
			if (nsvHost.isEnabled()) {
				final int scrollRange = nsvHost.getScrollRange();
				if (scrollRange > 0) {
					info.setScrollable(true);
					if (nsvHost.getScrollY() > 0) {
						info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD);
					}
					if (nsvHost.getScrollY() < scrollRange) {
						info.addAction(AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD);
					}
				}
			}
		}

		@Override
		public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) {
			super.onInitializeAccessibilityEvent(host, event);
			final ApptentiveNestedScrollView nsvHost = (ApptentiveNestedScrollView) host;
			event.setClassName(ScrollView.class.getName());
			final AccessibilityRecordCompat record = AccessibilityEventCompat.asRecord(event);
			final boolean scrollable = nsvHost.getScrollRange() > 0;
			record.setScrollable(scrollable);
			record.setScrollX(nsvHost.getScrollX());
			record.setScrollY(nsvHost.getScrollY());
			record.setMaxScrollX(nsvHost.getScrollX());
			record.setMaxScrollY(nsvHost.getScrollRange());
		}
	}
}
